The plant growth promoting fungus Penicillium sp. GP16-2 enhances the growth and confers protection against Cucumber mosaic virus in tobacco

Plant growth promoting fungi (PGPF) have received considerable attention in the recent years due to not only promote plant growth but also potentiate systemic resistance against different plant pathogens. In the existent study, we examined whether a PGPF, Penicillium sp. GP16-stimulates growth and Cucumber mosaic virus (CMV-Y) resistance in tobacco plants. The use of the barley grain inoculum (BGI) of GP16-2 significantly increased fresh and dry weight of tobacco plants 6 weeks after planting. Our results demonstrated that tobacco plants treated with BGI of GP16-2 or its culture filtrate (CF) showed significant decline in CMV severity and concentration in comparison with control plants. Increased transcription levels of only SA-inducible genes were noticed in the leaves of BGI treated plants using semi-quantitative RT-PCR. Moreover, the transcription levels of both PR1a and Coi1 genes were improved in CF treated plants. In conclusion, SA signaling cascade was played an important role in systemic resistance induced against CMV by BGI of GP16-2. On the other hand, CF of GP16-2 improved the expression of both SA- and JA- inducible genes, which led to the enhanced resistance against CMV infection.